Since the susceptibility of a conventional RF front-end module (FEM) against electrostatic discharge (ESD) is poor, the RF chip will be susceptible to damage by the electrostatic discharge.
Next, in the conventional RF front-end module, in order to protect the chip (or circuit) on an RF circuit, most of the RF front-end modules are equipped with an electrostatic protection unit (e.g. transient voltage suppressor, TVS). However, since the operating frequency of the transmission signal transmitted on the RF signal transmission line is getting higher and higher, only the electrostatic protection unit with low stray capacitance (parasitic capacitance) can be selected. However, when the capacitance value of the selected electrostatic protection unit is lower, the effectiveness of the electrostatic protection is lower. For example, when the operating frequency ranges from 2 GHz to 6 GHz, only the 0.2 pF of the electrostatic protection unit may be selected. When the electrostatic discharge protection capability of the chip is too low, and the electrostatic protection unit with a lower capacitance value (e.g. 0.2 pF) is selected in order to transmit signals with a higher operating frequency, the electrostatic protection unit will be unable to provide effective electrostatic protection, so that the chip will still be damaged by the electrostatic discharge due to the lower electrostatic protection capability of the electrostatic protection unit with the lower capacitance value.
Further, although the electrostatic discharge protection capability of the electrostatic protection unit with higher capacitance value (parasitic capacitance) is better than the lower capacitance value, the electrostatic protection unit with higher capacitance value will cause the RF efficiency to be reduced. In the other words, the electrostatic protection unit with higher capacitance value may cause the high frequency signal to be transmitted directly to the ground, and cause the RF efficiency to be reduced significantly.